I've got a 03 999S and as far as I have found out, the 02 to 04 999 and 999S are as 127bhp for the 999 and 139bhp for the 999S,their good for the money, I had the choice, it's a better looking bike than the 05,I think,and has the same power as a 999,05 but has the ohlins,
I have tried a couple of 03 999 and find them to have a very different power curve,the 999S will keep making more power all the way up to the red line,if it had one, in fact I find it better to change up a little,just to allow for the time it takes me to change gear,
ps you can find different power figuers,but I have seen these in print and it feels about right,
hope this helps